1. Field of the Invention
The present invention relates to a reproducing apparatus, and more particularly, it relates to processing of coded image data in slow reproduction.
2. Description of the Related Art
An apparatus, which encodes moving picture data by the MPEG (Moving Picture Experts Group) system and records it on a magnetic tape, is conventionally known (for example, refer to Japanese Patent Application Laid-Open No. 2002-10204: corresponding to U.S. Patent Application Publication No. U.S. 2001/0055469 A1). In Japanese Patent Application Laid-Open No. 2002-10204, a video tape recorder (VTR) having a function for slowly reproducing image data is disclosed, in which the image data is recorded by MPEG-coding. In Japanese Patent Application Laid-Open No. 2002-10204, for example, when image data is slowly reproduced at 1/N times a speed, a tape is transported at a speed 1/N times slower than normal reproduction, and a decoder performs processing at a timing of 1/N as compared with normal reproduction.
In MPEG-coding, coding is performed using intraframe coding (I picture) and interframe predictive coding (P picture, B picture), as well known. Further, according to the MPEG2 system, VBV-Delay information associated with code amount stored in a virtual buffer memory when performing decoding is added into a data stream. When data of each picture in the MPEG stream is decoded, there is a possibility that the data in the memory may suffer underflow, in the case where the data about code amount, which is decided on the basis of the VBV-Delay information, is not accumulated in the memory.
Therefore, when performing reproduction, the decoding of the MPEG data cannot be started until the data necessary for decoding is accumulated in the memory of the reproducing apparatus.
Furthermore, in the VTR disclosed in Japanese Patent Application Laid-Open No. 2002-10204, the tape is transported in slow reproduction at 1/N times a speed. Therefore, it takes much time at the time of starting slow reproduction until the data necessary for decoding is accumulated in the memory as compared with normal reproduction. As a result of this, there is a problem that a waiting time until an image is displayed, becomes longer than in normal reproduction.